Home » Author Archives: Jos Dirksen (page 2)

Author Archives: Jos Dirksen

Akka Typed Actors: Exploring the receptionist pattern

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In this article we’ll explore another of Akka-Typed patterns. This time we’ll show you how you can use the receptionist patterns. This is the third and last article on a series on Akka-Typed. The other two articles can also be found on this site. If you don’t know anything about Akka-Typed yet, it’s a good idea to first read the ...

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Two-way SSL (client certificates) with Scalatest

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At work we recently added the option to authenticate machine to machine communication using client certificates (two-way ssl). While this was relatively easy to set up and access programatically from different programming languages, we ran into some difficulties getting our integration test up and running. We wanted to have a couple of tests to make sure the information from the ...

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Akka Typed Actors: Exploring the receiver pattern

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In the previous article we looked at some of the basic features provided by Akka Typed. In this article and the next one we’ll look a bit closer at some more features and do that by looking at the two different patterns provided by Akka Typed: the Receiver and the Receptionist pattern. If you’re new to Akka Typed, it might ...

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Akka Typed: First steps with typed actors in Scala

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With the [release of Akka 2.4.0| http://akka.io/news/] a couple of weeks ago the experimental Akka Typed module was added. With Akka Typed it is possible to create and interact with Actors in a type safe manner. So instead of just sending messages to an untyped Actor, with Akka Typed we can add compile time type checking to our Actor interactions. ...

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Listen to notifications from Postgresql with Scala

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In the past I’ve written a couple of articles (Building a REST service in Scala with Akka HTTP, Akka Streams and reactive mongo and ReactiveMongo with Akka, Scala and websockets) which used MongoDB to push updates directly from the database to a Scala application. This is a very nice feature if you just want to subscribe your application to a ...

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Scala typeclass explained: Implement a String.read function

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In this short article I’d like to explain how you can use the typeclass pattern in Scala to implement adhoc polymorphism. We won’t go into too much theoretical details in this article, the main thing I want to show you is how easy is really is to create a flexible extensible model without tying your domain model to specific implementation ...

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Easy validation in Scala using Scalaz, Readers and ValidationNel

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I’m working on a new book for Packt which shows how you can use various Scala frameworks to create REST services. For this book I’m looking at the following list of frameworks: Finch, Unfiltered, Scalatra, Spray and Akka-HTTP (reactive streams). While writing the chapters on Finch and Unfiltered I really liked the way these two frameworks handled validation. They both ...

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Backpressure in action with websockets and akka-streams

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So in the previous article I showed how you could create a websocket server using akka-streams. In this follow up article we’ll look a bit closer on how backpressure works with websockets (and probably any TCP based protocol on top of akka). To show you this we’ll use the same setup as we did in the article on visualizing backpressure. ...

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Migrate sonar data from old to new sonar version

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At my current project we were setting up a new buildserver. One of the things we had to do was move an old sonar implementation running on top of H2 to a new version running on Oracle. The problem was that just migrating the data is nearly impossible to do when you start with H2, and when the versions were ...

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Using Go to build a REST service on top of mongoDB

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I’ve been following go (go-lang) for a while now and finally had some time to experiment with it a bit more. In this post we’ll create a simple HTTP server that uses mongoDB as a backend and provides a very basic REST API. In the rest of this article I assume you’ve got a go environment setup and working. If ...

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